A block is located at $A$ on the frictionless surface ABC shown, and two identical springs connect it to fixed points $D$ and $E,$ as shown. Given that the block starts at rest $($at A$),$ use Conservation of Total Energy to find:

$($a$)V_B($speed of the block when it reaches B$),$ and

$($b$)V_c($speed of the block when it reaches c$)$

Be sure to explain briefly why Gonservation of Total Energy is valid in this problem.